NavList:

From the star identification in previous post, the moons apparent position in the photo is:
23h 48m 44s RA and 5.0748902 d N Dec.

With the moon approximately on the horizon, a given altitude of 220 mi, known radius of earth and distance from moon to center of the earth a parallax of 1 degree is predicted. It lowers the apparent position by 1 degree. Dec RA coordinate system is oriented at close to 45 degree angle to photo. (0h RA passes through Uranus and 28 Piscium) So actual moon position is .707d ( 45d triangle) higher in both Dec and RA.

Estimated moon position at time of photo:
5.78d N Dec
23h 51m 34s RA

From Almanac this gives based on Dec a time of GMT 3/6/11 11h 20m 30s

From Almanac this gives based on GHA a time of GMT 3/6/11 11h 14m 57s

split the differenc and call it GMT 3/6/11 11h 17.5m for time of the photo.

It may be that more careful distribution of the parallax between Dec and RA would improve the agreement of the time for Dec and RA measurements, but already 6m seems pretty good considering the circumstances.

Dave Fleming

----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------